As it is found in nature, and does not alter during manufacturing processes, graphite is shiny, dark to medium gray in color, brittle and electrically conductive. A wide range of industries use graphite in product formation and the type of graphite used will depend on the intended application of the product.
In its natural form, there are three different types of graphite-crystalline flake, which is flat with hexagonal edges, amorphous, which is very flaky, and lump, which is found in underground veins and fissures. Different uses for graphite are in both commercial and industrial applications. The most popular use for graphite is to make pencil lead. However, this mineral’s applications are abundant within the industrial sector. In powder form, it acts as an effective dry lubricant, and is used in steel casting as a die lubricant to ease the part ejection.
When combined with alumina and zirconia, graphite forms stopper rods, sub-entry nozzles and ladle shrouts. The nuclear, chemical, electrical, electronics, automotive, aerospace and mechanical industries all use graphite in products like paints, batteries, brake linings for large non-automotive vehicles and laptop components.
Containers used to hold extremely hot liquids and materials called crucibles are often made of graphite, since it can withstand extremely high temperatures without burning, melting or chemically changing.
For most graphite products, graphite is manufactured synthetically, which does result in some different physical properties but it is still an effective conductor of electricity and heat. In addition to natural graphite’s uses, the synthetic form proves very valuable in products used for steel making. Since graphite is electrically conductive, it serves as material for electrodes in electric arc furnaces, which carry electricity and melt scrap steel as part of the die casting process.
Carbon is expensive, so graphite often serves as an alternative to carbon additives. Graphite electrodes are also used in printing processes. They are coated in a thin layer on wax impressions, underneath a copper layer. It gives the negative electrical connection used for electrolysis. Graphite is also commonly seen within nuclear applications to absorb neutrons, which aids in moderating a nuclear reaction.
One of the main benefits of graphite products are their high recycling ability. Products and leftover scraps may be melted down and reused multiple times. A combination of used and new graphite is ground into fine powder by crushers. It is usually mixed with other materials, and formed into different shapes by extrusion, die molding or cold isostatic pressing. The products are then heat treated in a baking oven, where the graphite goes through carbonization.